Method and system for adjusting lapping of a transducer using a disk windage

ABSTRACT

A method and system for providing transducer(s) including a disk structure and having an air-bearing surface (ABS) are described. The disk structure resides a distance from the ABS and has a disk dimension substantially perpendicular to the ABS. Lapping control and disk windage ELGs are provided. The lapping control ELG has first and second edges first and second distances from the ABS. The disk windage ELG has edges different distances from the ABS. A difference between these edges corresponds to the disk dimension. A windage resistance of the disk windage ELG is measured and a disk windage determined. The disk windage corresponds to a difference between designed and actual disk dimensions perpendicular to the ABS. A lapping ELG target resistance is determined based on the disk windage. The transducer is lapped. Lapping is terminated based on a resistance of the lapping control ELG and the lapping ELG target resistance.

BACKGROUND

Conventional magnetic heads typically employ lapping to fabricatestructures within the head. In order to control lapping an electroniclapping guide (ELG) is typically used. FIG. 1 depicts a top view of aconventional ELG 10. The conventional ELG 10 is essentially a resistivestripe. Thus, the conventional ELG 10 is coupled with pads/leads 14 and16 that are used to provide electrical connection to the conventionalELG 10. Using the pads/leads 14 and 16 the resistance of theconventional ELG 10 may be determined. The conventional ELG has a lengthl from the surface 12 being lapped. As lapping continues, the surface 12is worn away, and the length of the conventional ELG 10 decreases. Asthe length is reduced, the resistance of the conventional ELG 10increases. Using the resistance of the conventional ELG 10, it can bedetermined when lapping should be terminated.

For example, energy assisted magnetic recording (EAMR) transducer istypically lapped during fabrication. A conventional EAMR transducerincludes not only magnetic components, such as poles, coils, andshields, but also energy-delivery components. An EAMR transducer mayinclude optical components gratings, waveguides and near-fieldtransducers (NFTs). FIG. 2 depicts a portion of a conventional NFT 20. Aconventional NFT 20 typically includes a disk portion 22 and a pinportion 24. The disk portion 22 is wider in the direction parallel tothe air-bearing surface (ABS) than the pin portion 24. Lapping may beused to control the length, l, of the pin portion 24 of the NFT, as wellas other lengths such as the throat length of the pole (not shown inFIG. 2).

FIG. 3 is a flow chart depicting a conventional method 30 for performinglapping using the conventional ELG 10. The lapping performed in themethod 30 may be used in fabricating the conventional NFT 20. Theresistance of the conventional ELG 10 is measured during lapping of thetransducer, via step 32. The current length of the conventional ELG 10is determined based upon the resistance measured in step 32 and thesheet resistance of the conventional ELG 10, via step 34. Thus, afterstep 34, the length corresponding to a particular measured resistancefor the conventional ELG 10 is known. Alternatively, step 34 couldsimply convert a desired length of the pin portion 24 to an ELG lengthand the ELG length to a desired target resistance of the conventionalELG 10.

The lapping is terminated when the resistance of the conventional ELG 10indicates that the desired length or target resistance of theconventional ELG 10 has been reached, via step 36. Because theconventional ELG 10 and structure, such as a read sensor or pole, bothexist on the transducer being lapped, the lengths of the conventionalELG 10 and the structure change with lapping. Consequently, the lengthsof the read sensor or pole may also be set in step 36.

Although the conventional method 30 and conventional ELG 10 function,the desired length of the NFT may not be easily controlled to thedesired length. The dimensions of the conventional NFT 20 are desired tobe carefully controlled. For example, the distance between the diskportion 22 of the NFT 20 and the ABS (i.e. the length of the pin portion24) is desired to be closely controlled. Such control may be difficultto achieve using conventional manufacturing and lapping methods. Thus,fabrication of the conventional EAMR transducer may be challenging.

Accordingly, what is needed is an improved method for providing andusing an ELG in a magnetic transducer such as an EAMR transducer.

SUMMARY

A method and system for providing transducer(s) including a diskstructure and having an air-bearing surface (ABS) are described. Thedisk structure resides a distance from the ABS and has a disk dimensionsubstantially perpendicular to the ABS. The method and system includeproviding lapping control and disk windage ELGs. The lapping control ELGhas a first edge a first distance from the ABS and a second edge asecond distance from the ABS. The disk windage ELG has a third edge athird distance from the ABS and a fourth edge a fourth distance from theABS. A difference between the third edge and the fourth edge correspondsto the disk dimension. The method and system also include measuring awindage resistance of the disk windage ELG and determining a diskwindage corresponding to a difference between a designed disk dimensionperpendicular to the ABS and the disk dimension. The method and systemalso include determining a lapping ELG target resistance based on thedisk windage. The method and system also include lapping the transducerand terminating the lapping based on a resistance of the lapping controlELG and the lapping ELG target resistance.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 depicts a conventional ELG as used in a conventional magnetictransducer.

FIG. 2 depicts a conventional NFT in a conventional EAMR transducer.

FIG. 3 is a flow chart depicting a conventional method for performinglapping utilizing a conventional ELG.

FIG. 4 is a flow chart depicting an exemplary embodiment of a method forlapping a transducer including a disk structure.

FIG. 5 depicts an exemplary embodiment of a lapping control resistor anda windage ELG.

FIG. 6 depicts an electronic diagram of another embodiment of atransducer including a magnetic structure to be lapped using a lappingcontrol resistor and a windage ELG.

FIG. 7 is a flow chart depicting an exemplary embodiment of a method forlapping a transducer including a disk structure.

FIGS. 8-10 depict another exemplary embodiment of a transducer includinga magnetic structure to be lapped using a lapping control resistor and awindage ELG during fabrication.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 4 is a flow chart depicting an exemplary embodiment of a method 100for lapping a transducer including a disk structure. For simplicity,some steps of the method 100 may be omitted. FIGS. 5-6 depict exemplaryembodiments of a portion of transducers 120 and 120′ with which themethod 100 may be used. For clarity FIG. 5 is not to scale. FIG. 6 is acircuit diagram corresponding to the transducer 120 depicted in FIG. 5.Only certain portions of the transducer 120/120′ are shown in FIGS. 5-6.The transducer 120/120′ each includes at least one structure (not shownin FIGS. 5-6) on which lapping is to be performed. Although multiplestructures may be lapped, the method 100 and transducer 120/120′ relateto a structure for which the distance from the ABS is desired to be setby lapping. In the embodiment described, this structure is a diskstructure. For example, the method 100 may be used when lapping the pinportion of the NFT, which determines the distance between the diskportion of the NFT and the ABS. The disk portion of the NFT is the diskstructure in such an embodiment. Although termed a “disk” portion, theportion may have a shape other than a circle. The method 100 may also beused in fabricating other structures, particularly those such as disksor squares, which are symmetric. The method 100 is also described in thecontext of single transducers 120. However, the method 100 may be usedfor fabricating multiple transducers and/or multiple structures and mayemploy multiple ELG(s) at substantially the same time. The method 100 isalso described in the context of one ELG being used for each structurebeing fabricated. However, the method 100 may use one ELG for multiplestructures or vice versa.

Lapping control and disk windage ELGs are provided, via step 102. Thelapping control ELG is desired to have a resistance which changes duringlapping. Thus, the lapping control ELG has a first edge a first distancefrom the ABS and a second edge a second distance from the ABS. As usedherein the ABS may be the desired location of the ABS to which thetransducer 120 is lapped. Thus, the resistance of the lapping controlresistor may change during lapping of the transducer. For example, thelapping control resistor may be used to set the throat length of thepole. The disk windage ELG has a third edge a third distance from theABS and a fourth edge a fourth distance from the ABS. The differencebetween the third and fourth edges corresponds to a disk dimension. Insome embodiments, the disk dimension is the diameter of the disk asmeasured perpendicular to the ABS. Thus, the distance between the thirdand fourth edges of the disk windage ELG would equal the disk diameter.In other embodiments, the difference between the third and fourth edgesmay be another dimension of the disk. The disk windage ELG is used todetermine the disk windage. As used herein, the disk windage is thedifference between the actual disk dimension as measured using thewindage resistor and the calculated disk dimension used in designing themasks used in fabrication of the transducer 120. For example, the diskwindage may be the difference between the actual diameter of the diskportion of the NFT and the calculated diameter of the disk portion ofthe NFT used in designing the transducer 120.

FIG. 5 depicts the conventional transducer after formation of thelapping ELG and disk windage ELG. The transducer 120 includes a diskwindage ELG 122 having leads 128 and 130 and a lapping ELG having leads126 and 130. Thus, the ELGs 122 and 124 share a ground lead 130. Inother embodiments, the ELGs 122 and 124 need not share a ground lead.However, the resistances of the ground leads would be known. In theembodiment shown, the lapping ELG 124 and disk windage ELG have the sametrack width tw. In other embodiments, the track widths may differ.However, in such embodiments, the differences in track widths aregenerally desired to be known. In addition to sharing a ground lead 130,the remaining leads 126 and 128 are also matched. Stated differently,the leads 126 and 128 have the same resistance. In other embodiments,the leads 126 and 128 have known resistances. Further, the materialsused for the disk windage ELG 122 and the lapping control ELG may be thesame. As a result, the differences in resistance between the lapping ELG124 and the disk windage ELG 122 may be due to the differences inheight. More specifically, the height of the disk windage ELG may bedetermined based on the resistance of the disk windage ELG 124. The diskwindage ELG 124 is a distance pl from the ABS and has a stripe height,d, perpendicular to the ABS.

FIG. 6 depicts a circuit diagram of the transducer 120′. Thus, inaddition to the disk windage ELG 122′, lapping control ELG 124′ and pads126′, 128′, and 130′, resistors 131, 133, and 135 are shown. Resistors131, 133, and 135 represent lead and other resistances in the circuit.Also shown are a reader ELG 134 and pad 132. These components 132 and134 may be used in lapping a read transducer in a merged head. However,in other embodiments, such components 132 and 134 may not be included.

At least one windage resistance of the disk windage ELG 122 is measured,via step 104. Thus, the resistance of the disk windage ELG may bedetermined. Step 104 may be performed by a desired mechanism formeasuring resistance.

A disk windage is determined, via step 106. As described above, the diskwindage is the difference between a designed disk dimensionperpendicular to the ABS and the disk dimension. The actual diskdimension is determined based upon the resistance measured in step 104.First, the resistance measured in step 104 is used to determine thestripe height, d, of the disk windage ELG 122. If the lapping ELG 124and disk windage ELG 122 are formed of known, matching (or the same)material, the stripe height, d, of the disk windage ELG 122 may bedetermined based on the resistance of the disk windage ELG 122. Forexample, the stripe height, d, may be given by R_(s)T_(w)/(R−R_(l)),where R_(s)T_(w) is the slope of the resistance versus the inverse ofthe stripe height as predicted from the ELG measurement; R_(l) is theintercept of the resistance versus the inverse of the stripe heightpredicted from the ELG measurement; and R is the measured resistance ofthe disk windage ELG 122. Wafer final probe or other data may be used todetermine the sheet resistance-track width product R_(s)T_(w). R ismeasured in step 104. Thus, the resistance measured in step 104 may beused in determining the actual stripe height of the disk windage ELG122.

The stripe height of the disk windage resistor 122 may be converted tothe disk windage. Because the manner in which it is fabricated in step102, the disk windage ELG 122 has a stripe height that corresponds tothe disk dimension. In some embodiments, the stripe height is designedto be the same as the disk dimension. For example, the disk windage ELG122 may be designed such that the stripe height is equal to the diameterof the disk structure. The actual disk diameter in such embodiments isd. Thus, the actual diameter of the disk may be determined from theresistance of the windage ELG 122. The designed dimension (e.g.diameter) of the disk is known. The disk windage may be determined bycomparing the designed stripe height (i.e. the designed disk diameter)with the actual stripe height of the disk windage ELG 122.

A lapping ELG target resistance is determined based on the disk windage,via step 108. Step 108 may include updating a lapping ELG targetresistance that had previously been determined based on the designeddimensions of the disk. More specifically, the disk windage may be usedto adjust a calculated target resistance for the lapping ELG 124 toaccount for differences between the calculated disk diameter and theactual disk diameter.

The transducer 120 is lapped, via step 110. In general, lapping iscarried out substantially perpendicular to the ABS. For example, lappingmay be at an angle of approximately 89.5-90.5 degrees. Lapping is thenterminated based on a resistance of the lapping control ELG 124 and thelapping ELG target resistance, via step 112. More specifically, thelapping is terminated when the resistance of the lapping control ELG 124matches the lapping ELG target resistance.

Using the method 100, the lapping target resistance may be adjustedusing the disk windage. These adjustments allow for variations in thedisk of the NFT as actually fabricated to be accounted for. Use of thewafer final probe data in calculating the actual stripe height, d, fromthe windage resistance allows the adjustments to be fed forward. Thus,the corrections may be made easily. Further, in the configurationdepicted in FIGS. 5-6, no additional connections need be made duringlapping.

FIG. 7 is a flow chart depicting an exemplary embodiment of a method 150for fabricating a transducer including a disk structure. For simplicity,some steps of the method 100 may be omitted. FIGS. 8-10 depict exemplaryembodiments of a portion of a transducer 200 with which the method 150may be used. The transducer is fabricated on a slider (not shown inFIGS. 8-10). For clarity FIGS. 8-10 are not to scale. Only certainportions of the transducer 200 are shown in FIGS. 8-10. Morespecifically, only regions corresponding to the NFT and disk windage ELGare depicted. The transducers 200 each includes at least one structurefor which lapping is to be performed. Although multiple structures maybe lapped, the method 150 and transducer 200 relate to a structure forwhich the distance from the ABS is desired to be set by lapping. In theembodiment described, this structure is a disk structure. For example,the method 150 may be used when lapping the pin portion of the NFT,which determines the distance between the disk portion of the NFT andthe ABS. The disk portion of the NFT is the disk structure in such anembodiment. However, the method 150 may be used in fabricating otherstructures, particularly those such as disks or squares, which aresymmetric. The method 150 is also described in the context of singletransducers 200. However, the method 150 may be used for fabricatingmultiple transducers and/or multiple structures and may employ multipleELG(s) at substantially the same time. The method 150 is also describedin the context of one ELG being used for each structure beingfabricated. However, the method 100 may use one ELG for multiplestructures or vice versa.

Resistance sheet(s) are deposited, via step 152. Step 152 may includedepositing a conductive sheet, such as a sheet of Cr. The lappingcontrol and disk windage ELGs are defined from the resistance sheet, viastep 154. The disk windage ELG and the disk structure are formed using asingle mask.

For example, FIG. 8 depicts top (or plan) cross-section (or side) andABS views of the transducer 200 during step 154. The transducer 200 mayinclude cladding 202 and a core 204 from which a waveguide is formed. Inthe embodiment shown, a thin layer 206 of material has been deposited onthe core 204. However, in other embodiments, this layer may be omitted.The NFT film stack 210 is used in forming the NFT. The NFT film stack210 includes disk/pin portion film 212 and disk portion film 216,separated by another, stop layer 214. However, in other embodiments, asingle layer and/or another number and type of layers may be used forthe NFT. Also shown is ELG film 220. In some embodiments, both the diskwindage ELG and the lapping control ELG (not shown in FIGS. 8-10) areformed from the ELG film 220. However, in other embodiments, the diskwindage and lapping control ELGs may be formed from different layers. Inaddition, the ELG film 220 is shown as residing at substantially thesame level as the NFT film stack 210. Thus, both the NFT film stack 210and the ELG film 220 are shown as residing on the layer 206. However, inanother embodiment, the NFT film stack 210 and the ELG film 220 mayreside at different levels in the transducer 200. Also shown in FIG. 8is mask 230. The mask 230 is used in defining the disk structure of theNFT. Consequently, a portion of the mask 230 is shown as being circularin the plan view. However, in other embodiments, this portion of themask 230 may take on a different shape. A portion of the mask 230 alsoresides on the ELG film 230. The mask is shown as having a stripeheight, d, which corresponds to the diameter of the disk 230. Inaddition, the distance between the ABS and the edge of the mask closestto the ABS is the same for both portions of the mask 230. The mask 230is also shown as residing directly on the disk portion film 216 and theELG film 220. However, in other embodiments, one or more other layers(not shown) may reside between the disk portion film 216 and the mask230 and/or between the ELG film 220 and the mask 230.

FIG. 9 depicts the transducer 200 after step 154 has been performed.Thus, the disk portion 216′ has been formed. In addition, the diskwindage ELG 220′ is defined. The disk portion 216′ and disk windage ELG220′ are both defined using the mask 230′. in the embodiment shown, thefront edge 217 of the disk portion 216′ is the same distance from theABS as the front edge 221 of the disk windage ELG 220′. Further, thestripe height of the disk windage ELG 220′ is substantially the same asthe diameter of the disk portion 216′. However, in other embodiments,the front edge 221 of the disk windage ELG 220′ may be offset from thefront edge 217 of the disk portion 216′. For example, in someembodiments, the front edge 221 of the disk windage ELG 220′ may becloser to the ABS than the front edge 217 of the disk portion 216′. Anysuch offset is generally desired to be designed to be known andrelatively small.

At least one windage resistance of the disk windage ELG 220′ ismeasured, via step 156. Thus, the resistance of the disk windage ELG maybe determined. Step 156 is analogous to step 104 of the method 100.

The disk windage is determined, via step 158. As described above, thedisk windage is determined based upon the resistance measured in step156. Step 158 is analogous to step 106 of the method 100.

The lapping ELG target resistance is determined based on the diskwindage, via step 160. Step 160 is analogous to step 108 of the method100.

The transducer 200 is lapped, via step 162. During lapping, theresistance of the lapping control ELG is measured, via step 164. Also instep 164, the resistance of the disk windage ELG 220′ may optionally bemeasured during lapping. The disk windage ELG resistance may be measuredin step 164 if the front 221 of the disk windage ELG 220′ is closer tothe ABS than the front 217 of the disk. However, in other embodiments,the resistance of the disk windage ELG 220′ may be measured when thefronts 217 and 221 are the same distance from the ABS. The resistance ofthe lapping control ELG determined in step 164 is compared against thetarget resistance, via step 166. Also in step 166, it may be determinedwhether the resistance of the disk windage ELG 220′ has changed. Thismay be accomplished by comparing the last measured resistance of thedisk windage ELG 220′ with a previously-measured resistance. Steps 164and 166 may be carried out multiple times during lapping in step 162.

Lapping is then terminated based on the resistance of the lappingcontrol ELG and the lapping ELG target resistance and/or based on achange in the disk windage ELG resistance, via step 168. Morespecifically, the lapping may be terminated when the resistance of thelapping control ELG matches the lapping ELG target resistance. In otherembodiments, the lapping may be terminated when the resistance of thedisk windage ELG 220′ changes. Terminating lapping when the disk windageELG 220′ changes resistance may prevent the pin portion 214 of the NFTfrom being inadvertently lapped too closer to the disk 220′ and maypreclude removal of a portion of the disk portion 216′ of the NFT. Inother embodiments, the lapping may be terminated when the first of thetarget resistance is reached and a change in the disk windage ELGresistance occurs.

Using the method 150, the lapping target resistance may be adjustedusing the disk windage. These adjustments allow for variations in thedisk of the NFT as actually fabricated to be accounted for. Use of thewafer final probe data in calculating the actual stripe height, d, fromthe windage resistance allows the adjustments to be fed forward. Thus,the corrections may be made easily. Further, in the configurationdepicted in FIGS. 5-6, no additional connections need be made duringlapping. In addition, overlapping of the disk portion 216′ of the NFTand/or the pin portion 214 may be prevented.

We claim:
 1. A method for providing at least one transducer including adisk structure and having an air-bearing surface (ABS), the diskstructure residing a distance from the ABS and having a disk dimensionsubstantially perpendicular to the ABS, the method comprising: providinga lapping control ELG and a disk windage ELG for each of the at leastone transducer, the lapping control ELG having a first edge a firstdistance from the ABS and a second edge a second distance from the ABS,the disk windage ELG having a third edge a third distance from the ABSand a fourth edge a fourth distance from the ABS, a difference betweenthe third edge and the fourth edge corresponding to the disk dimension;measuring a windage resistance of the disk windage ELG; determining adisk windage based on the windage resistance, the disk windagecorresponding to a difference between a designed disk dimensionperpendicular to the ABS and the disk dimension; determining a lappingELG target resistance based on the disk windage; lapping the transducer;and terminating the lapping based on a resistance of the lapping controlELG and the lapping ELG target resistance.
 2. The method of claim 1wherein the disk structure is a disk of a near-field transducer.
 3. Themethod of claim 1 wherein the lapping control ELG has a first trackwidth and the disk windage ELG has a second track width substantiallyequal to the first track width.
 4. The method of claim 1 wherein thelapping control ELG is coupled with a first plurality of leads having afirst leads resistance, the disk windage ELG is coupled with a secondplurality of leads having a second leads resistance, the first leadsresistance being substantially equal to the second leads resistance. 5.The method of claim 4 wherein the first plurality of leads and thesecond plurality of leads include a common ground lead.
 6. The method ofclaim 1 wherein the step of providing the lapping control ELG and thedisk windage ELG further includes forming the disk structure and thedisk windage ELG using a single mask.
 7. The method of claim 1 whereinthe step of terminating the lapping further includes: measuring theresistance of the lapping control ELG during the lapping step; comparingthe resistance to the lapping ELG target resistance; and terminating thelapping based on the comparing step.
 8. The method of claim 1 whereinthe step of providing the lapping control ELG and the disk windage ELGfurther includes: depositing a resistance sheet; and defining thelapping control ELG and the disk windage ELG from the resistance sheet.9. The method of claim 1 wherein the fourth distance is substantiallyequal to the second distance.
 10. The method of claim 1 furthercomprising: measuring the windage resistance of the disk windage ELGduring lapping; and optionally terminating lapping based on a change inthe windage resistance during lapping.
 11. A method for providing atleast one transducer including a near-field transducer (NFT) having adisk structure and having an air-bearing surface (ABS), the diskstructure residing a distance from the ABS and having a disk dimensionsubstantially perpendicular to the ABS, the method comprising: providinga lapping control ELG and a disk windage ELG for each of the at leastone transducer, the lapping control ELG coupled to a lapping ELG leadand a ground lead, the lapping control ELG having a first edge a firstdistance from the ABS, a second edge a second distance from the ABS, anda track width, the disk windage ELG coupled to a disk windage lead andthe ground lead, the disk windage ELG having a third edge a thirddistance from the ABS, a fourth edge a fourth distance from the ABS, andthe track width, a difference between the third edge and the fourth edgecorresponding to the disk dimension, the disk windage lead and thelapping ELG lead having substantially the same resistance, the step ofproviding the disk windage ELG further including defining the diskwindage ELG and the disk dimension using a single mask; measuring awindage resistance of the disk windage ELG; determining a disk windagebased on the windage resistance, the disk windage corresponding to adifference between a designed disk dimension perpendicular to the ABSand the disk dimension; determining a lapping ELG target resistancebased on the disk windage; lapping the transducer; and measuring theresistance of the lapping control ELG during the lapping; andterminating the lapping based on the resistance of the lapping controlELG and the lapping ELG target resistance.